HR: 0830h
AN: OS41C-0820    [PDF]
TI: A New Tool for Probing Thermohaline Fine Structure in the Ocean: Seismic Reflection Profiling of the Labrador Current/North Atlantic Current Front
AU: * Holbrook, W S
EM: steveh@uwyo.edu
AF: University of Wyoming, Department of Geology and Geophysics, Laramie, Wy 82071 United States
AU: Paramo, P
EM: paramo@uwyo.edu
AF: University of Wyoming, Department of Geology and Geophysics, Laramie, Wy 82071 United States
AU: Pearse, S
AF: University of Wyoming, Department of Geology and Geophysics, Laramie, Wy 82071 United States
AU: Schmitt, R W
EM: rschmitt@whoi.edu
AF: Woods Hole Oceanographic Institute, Physical Oceanography, Woods Hole, MA O2543 United States
AB: We present acoustic images of thermohaline structure in the ocean created from marine multichannel seismic reflection profiles across the major oceanographic front between the Labrador Current and the North Atlantic Current. The images show that distinct water masses can be mapped, and their internal structure imaged, using low-frequency acoustic reflections. The reflections are generated by sound-speed contrasts at interfaces across which temperature changes by up to 3 degrees C. Returns from reflection coefficients (RC) as low as 0.0001, corresponding to sound speed changes of 0.3 m/s (temperature changes of ~0.1 degrees C), can be imaged. The warm/cold front is characterized by strong (RC ~ 0.004; 12 m/s), east-dipping reflections generated by thermohaline intrusions in the upper 1000 m of the ocean. Regions away from the front show weaker undulating reflectors suggestive of internal waves in the thermocline and submesoscale eddies beneath the thermocline. Our results imply that standard low frequency marine seismic reflection techniques can provide excellent spatial resolution of important oceanic phenomena, including thermohaline intrusions, internal waves and eddies.
DE: 0935 Seismic methods (3025)
DE: 1724 Ocean sciences
DE: 1734 Seismology
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting